Limitations of Serum Ferritin in Diagnosing Iron Deficiency in Inflammatory Conditions

Figure 1

Normal iron homeostasis in the reticuloendothelial macrophage. Macrophages phagocytose aged or damaged red blood cells, using heme oxygenase 1 to release iron from heme, a recycling process that accounts for approximately 90% of the body’s daily iron needs. Iron is rapidly released to circulating transferrin or, when present in excess, stored in ferritin. When required, ferritin is degraded in the lysosomes via a process called ferritinophagy and the iron is released. Iron(II) is exported from the macrophage via ferroportin in the cell membrane in a process coupled to reoxidation from iron(II) to iron(III) by membrane-bound ceruloplasmin. Iron(III) is then loaded onto transferrin for transport in the plasma.